The invention relates to machine tools which comprise a rotary workpiece spindle, inter alia to lathes, particularly digitally controlled lathes.
Machines of this kind can be used for internal machining operations, using boring tools, and external machining operations, using turning tools. They are frequently equipped with two separate tool turrets, i.e. a boring tool turret and a turning tool turret, so as to prevent unused tools from interfering with the workpiece.
Machine tools have been constructed wherein a main boring tool turret is mounted for pivoting about an axis parallel to that of the workpiece spindle on bracket which can be moved relative to the workpiece spindle in two directions, one parallel and the other at an angle to the workpiece spindle, and an auxiliary or turning tool turret is borne by the main turret and likewise mounted for pivoting about an axis parallel to that of the workpiece spindle so that each tool on the auxiliary turret can be selectively brought into the operative position while the main turret is in a predetermined inoperative angular position. However in the known machine, the auxiliary or turning tool turret is coaxially mounted on the main or boring tool turret, so that when the tools are in the inoperative position they are not always sufficiently disengaged from the inoperative tools and from the workpiece or the lathe tailstock, when work is carried out between centres.
The aim of the invention is to provide a machine tool of the aforementioned kind which is free from disadvantages thereof.